Every human cell requires a constant supply of oxygen to maintain cellular structure and homeostasis. This supply is primarily provided by hemoglobin, which carries inspired oxygen from the pulmonary capillaries to the tissues. In cases where a patient's lungs are unable to transfer adequate amounts of oxygen to circulating erythrocytes, severe hypoxia results and can quickly lead to severe organ injury and death.
Restoration of blood oxygen tension is paramount to resuscitation of the majority of pathophysiologic states. Some clinical states, such as lung injury, airway obstruction, and intracardiac mixing, exhibit hypoxemia and desaturation refractory to medical efforts to restore levels of oxygen saturation sufficient to limit ischemic injury. Ischemic injury may take place within minutes or seconds of insufficient oxygen delivery. In these conditions, low oxygen tension can result in end-organ dysfunction, failure, and mortality. The ability to augment oxygenation quickly and non-invasively would have dramatic implications on the morbidity and mortality from acute hypoxia, in addition to a number of other clinical situations.
Conventional attempts to restore oxygen levels in patients utilize supportive therapy of the patient's respiratory system, most commonly by way of mechanical ventilation. However, patients with lung injury, comprising a significant population of intensive care unit patients, have difficulty exchanging oxygen across damaged lungs or airways. This requires clinicians to increase ventilator pressures, often causing further lung injury and systemic inflammation. Significant morbidity and mortality has been associated with ventilator induced lung injury, and barotrauma to the lungs is often necessitated by inadequate systemic oxygen delivery. The ability to non-invasively supplement even small percentages of oxygen delivery may significantly reduce the morbidity of mechanical ventilation.
Furthermore, emergency efforts to deliver oxygen to a patient are often inadequate and/or require too long to take effect, either due to lack of an adequate airway or overwhelming lung injury. This results in irreversible injury to the brain and other organs. Initiation of rescue therapy in these patients is burdensome and time consuming, and is available only at a limited number of specialized health care centers.